Over the last several years great advances have been made in the feasibility and success of balloon angioplasty, both in peripheral arteries and coronary arteries. Percutaneous transluminal coronary angioplasty (PTCA) has now become an established technique for treatment of atherosclerotic obstructions in coronary arteries. For many patients, this procedure eliminates the need to undergo coronary bypass
Recent studies have suggested that the effectiveness of balloon angioplasty (including PTCA) increases if the inflation of the balloon can be more gradual and if the duration of balloon inflation can be lengthened. Since conventional balloons entirely occlude the artery when inflated (including any side branches in the artery adjacent the balloon), the duration of balloon inflation often is limited by patient tolerance of chest pain and hemodynamic or electrical instability, as well as eventual tissue necrosis distally of the balloon if the circulation is cut off too long.
A variety of techniques have been proposed to mitigate these limitations, including various drug treatments (e.g., pretreatment with lidocaine, nitroglycerin, etc.), retroperfusion via the coronary sinus, and even the use of general anesthesia. One technique that mitigates many of these limitations is the use of a perfusion balloon catheter, such as that developed by Stack (see, e.g., D. Kereiakes & R. Stack, "Perfusion Angioplasty," Textbook of Interventional Cardiology (E. Topol, ed., 1990)). In these types of balloon catheters, the catheter shaft includes side holes both proximally and distally of the balloon. These holes allow blood to enter the catheter lumen proximally of the balloon and then pass through the lumen into the artery distally of the balloon, thus preserving some blood flow even when the balloon is inflated The shaft of such perfusion balloon catheters, however, is necessarily relatively large (in order to permit a significant amount of blood flow therethrough), and the catheter consequently is less flexible, limiting its use and effectiveness. Moreover, side branches of the artery may still be occluded by the balloon if the stenotic segment is near or spans such a branch.